A225068 Least octagonal (8-gonal) number that is the product of n octagonal numbers greater than 1.

8, 1408, 2165800, 37333296, 19384601600, 69370076160, 69370076160, 56288711711232000, 7917914554368000000, 199449790781142859776

Offset

1,1

Links

Table of n, a(n) for n=1..10.

Lars Blomberg, Table of n, a(n) with solutions for n=1..10

Example

Let oct(n) = n*(3n-2). Then
a(1) = 8 = oct(2).
a(2) = 1408 = oct(22) = oct(2) * oct(8).
a(3) = 2165800 = oct(850) = oct(4) * oct(5) * oct(17).
a(4) = 37333296 = oct(3528) = oct(3)^2 * oct(8) * oct(13).
a(5) = 19384601600 = oct(80384) = oct(2)^2 * oct(5) * oct(14) * oct(53).
a(6) = 69370076160 = oct(152064) = oct(3)^3 * oct(4) * oct(7) * oct(22).

Crossrefs

Cf. A000567 (octagonal numbers).

Cf. A212616, A212617, A225066-A225070 (3-, 5- to 10-gonal cases).

Sequence in context: A283902 A064073 A282889 * A270145 A201492 A172938

Adjacent sequences: A225065 A225066 A225067 * A225069 A225070 A225071

Keyword

nonn,more

Author

T. D. Noe, May 01 2013

Extensions

Corrected a(4) and added a(7)-a(10) by Lars Blomberg, Sep 21 2013

Status

approved